Polymerization induced shaping of Pickering emulsion droplets: From simple hollow microspheres to molecularly imprinted multicore microrattles

- The polymerization induced shaping in Pickering emulsion droplets is proposed.
- Bisphenol A imprinted spheres with multicore rattle-like structure are obtained.
- The evolution of multicore sphere triggered by imprinting molecules is revealed.
- The spheres are unique which can fast and accurately bind with target molecules.

The design and fabrication of polymer microspheres with structural complexity in Pickering emulsion systems is a pioneering topic in recent years. Herein we report a synthesis of structured and molecularly imprinted multicore rattle-type microspheres through a facile method based on the Pickering emulsion polymerization using silica nanoparticles as the only stabilizer. The void inside the sphere was induced by the polymerization-driven phase separation approach tailoring by the interface interaction. However, the imprinting template of bisphenol A (BPA) is found to serve also as the heterogeneous nuclei, whose superimposition on the polymerization induced phase separation creates the opportunities for the formation of the multicores encapsulated in the shell. A simple adjustment on the composition of the oil phase enabled the evolution of sphere internal structures from single void to multicores. Specifically, the reversibly incorporated BPA on the polymer spheres can be removed by extraction with the molecular information left and immobilized by crosslinking as the imprinted sites. The imprinted spheres can be used to selectively rebind BPA, which was comprehensively evaluated by a batch of rebinding experiments. The rattle-like microspheres recognized BPA molecules from their analogues and effectively removed them from the matrix with accelerated adsorption kinetics, which shows potential applications in the environmental or analytic fields where the removal or separation of BPA as an endocrine-disrupting chemical is in high demand.

In this work, the molecularly imprinted multicore rattle-type microspheres were fabricated via Pickering emulsion polymerization. Bisphenol A was selected as the imprinting template since it served as both the template molecule and the nucleation agent. The polymerization induced phase separation creates the opportunities for the formation of the multicores encapsulated in the shell. With the well recognition accuracy and selective efficiency, the rattle-type spheres also show remarkably accelerated adsorption kinetics.101